The light receiving circuit for converting an optical signal into an electrical signal is widely used in various fields. For instance, the photocoupler equipped with the light receiving circuit is widely used in electronic devices for industrial, communication, and household use.
In these electronic devices, signals are mutually transferred between different power supply systems such as DC voltage, AC voltage, and telephone line power supply systems.
Use of a photocoupler enables transfer of electrical signals between different power supply systems insulated from each other.
In the light receiving circuit installed in e.g. a photocoupler, the current of the light receiving circuit increases with the increase of the input level of the pulse optical signal. Thus, the delay time of the signal increases. This may increase the output pulse width distortion.